The present invention relates to an endoscopic tissue collecting instrument suitable for use typically in a biopsy of the pancreas, the liver and other organ by being inserted into and removed from a treatment instrument insertion channel in an endoscope.
FIG. 15 shows the distal end portion of a Menghini needle used as an endoscopic tissue collecting instrument. The Menghini needle comprises a rod-shaped needle shaft 10 having a pointed end 11 and a tissue retaining recess 12 formed in the lateral side of an area close to the needle end 11 and into which an excised tissue specimen is retained.
A cannula or outer sheath 20 is fitted over the needle shaft 10 to be capable of moving back and forth along the longitudinal axis, and it has an annular blade 21 formed on the inner circumference of the tip for cutting off or excise the tissue retained in the recess 12.
FIGS. 16 and 17 show how a tissue specimen for biopsy is collected with the endoscopic tissue collecting instrument thus constructed as the Menghini needle. First, as shown in FIG. 16, the outer sheath 20 pierced into the tissue 100 is pulled back a little so that the desired portion of the tissue 100 is caught in the recess 12. Then, as shown in FIG. 17, the outer sheath 20 is quickly pushed forward to cut off the retained portion of the tissue 100 as a tissue specimen 101.
This endoscopic tissue collecting instrument is designed such that the blade 21 cuts off or excises the tissue 100 perpendicularly to a direction in which the outer sheath 20 is pushed forward. For this reason, in practice, when the outer sheath 20 is being pushed forward, the tissue 100 is also pushed forward as shown in FIG. 18, and it often occurs that only a small volume of the tissue specimen 101 can be collected in the recess 12.
An object, therefore, of the present invention is to provide an endoscopic tissue collecting instrument which can collect a large tissue specimen by cutting the tissue positively with a blade provided to the outer sheath.
An endoscopic tissue collecting instrument according to the present invention is designed so that a blade can apply a cutting force to a tissue obliquely.
For example, a blade is formed at the distal end of an outer sheath to be oblique to the circumferential direction of the outer sheath. Because of this design, if the outer sheath is pushed forward to cut off a tissue, the blade slides obliquely relative to the tissue as it advances. Accordingly, the tissue can be severed without being pushed forward by the outer sheath and instead it is cut positively enough to permit the collection of a large volume of tissue specimen.
For example, a blade formed at the distal end of the outer sheath rotates about the longitudinal axis while moving along it over the tissue retaining recess. As a result, the tissue of interest is not pushed forward but can be cut easily and positively to collect a large volume of tissue specimen.
Preferably, an endoscopic tissue collecting instrument includes a needle shaft having a needle tip pointed forward, and a tissue retaining recess recessed laterally in an area close to the needle tip, and an outer sheath fitted over the needle shaft so as to be movable back and forth in a longitudinal axis direction relative to the needle shaft. The outer sheath has a blade at its distal end for cutting off a tissue retained in the tissue retaining recess. The blade formed at the distal end of the outer sheath is oriented obliquely relative to a circumferential direction of the outer sheath.
A radially inner edge of the distal end of the outer sheath may be saw-toothed to define the blade, or the distal end of the outer sheath may be obliquely cut to define the blade.
Preferably, an endoscopic tissue collecting instrument includes a needle shaft having a needle tip pointed forward, and a tissue retaining recess recessed laterally in an area close to the needle tip, and an outer sheath fitted over the needle shaft so as to be movable back and forth in a longitudinal axis direction relative to the needle shaft. The outer sheath having a blade at its distal end for cutting off a tissue retained in the tissue retaining recess. When the blade is moved across the tissue retaining recess, the outer sheath is rotated about the longitudinal axis direction while being moved in the longitudinal axis direction.
The outer sheath may be movably passed through a support tube to be fixed to an entrance of a treatment instrument insertion channel of an endoscope, and a tab projecting from a basal end portion of the outer sheath may be in engagement with a spiral groove formed in the support tube.
In this case, a slider knob may be provided for manipulation to move the tab in the longitudinal axis direction, or a rotating knob may be provided for manipulation to rotate the tab about the longitudinal axis direction.
An aspiration channel may be provided to extend through the needle shaft, and communicate with a rear of the tissue retaining recess.
The present disclosure relates to the subject matter contained in Japanese patent application Nos. Hei. 11-363609 (filed on Dec. 22, 1999), and 2000-8439 (filed on Jan. 18, 2000), which are expressly incorporated herein by reference in their entireties.